This application claims the priority of German Application No. 101 33 730.2, filed Jul. 11, 2001, the disclosure of which is expressly incorporated by reference herein.
The present invention concerns fasteners for joining a windshield to a fuselage side frame of the viewing port of an aircraft. Specifically, the cockpit frame of a helicopter, consisting of a fastening element fixed in place at a segment of the peripheral region of the windshield through a bore hole, through a congruent bore hole of the fuselage side frame, and through a frame fixture with a spring device. The peripheral slot between the fuselage side frame and the windshield is filled with a sealant.
Various connecting devices are known for producing a detachable mechanical connection between two components. Their application depends upon the function and use of the components to be joined. Especially with the mechanical connection of two components with various thermal expansion coefficients in a relatively broad temperature spectrum, special standards are imposed upon the connecting devices.
In aircraft construction, for example, in the region of the outer skin of the fuselage structure, a windshield (also referred to as window pane) consisting of a transparent plastic material for covering a corresponding viewing port (also referred to as window opening) is connected to the fuselage structure with the fuselage side framework by means of mechanically detachable connecting devices. Fuselage side frames and windshields are components with different thermal expansion coefficients. In particular, the glue between the frame and the windshield has a possible expansion of up to a multiple of that of a width of the slit in which it is seated. During the aircraft takeoff up until a cruising altitude is reached, or during the landing, or, possibly, during heating up by the sun when the aircraft is sitting on an apron, a relatively wide temperature gradient is acting on the affected components. The consequences are strong mechanical stresses in the connecting devices as well as in the corresponding individual components. Aircraft to be considered are fixed wing aircraft and rotary wing aircraft, especially helicopters.
As a consequence of these stresses, the danger of crack formation in the connecting device and/or the windshield could arise, and/or the fuselage side frame could become deformed in the area of the outer skin, as consequence of which, the sealing of the windshield could be detrimentally affected.
Use of the so-called Camloc connections as a connecting mechanism for windshields and fuselage side frames to counteract these stresses is known. A Camloc connection operates according to the principle of a bayonet lock outfitted with a spring. The functional principle corresponds to latching a bolt (pin) of a fastening element against the action of a spring force in the cavity of a fixed fastening part.
The known Camloc connection as a connecting device is here configured such that, for producing the connection, the head of the fastening element must be pressed in the direction against the spring, and then fastened by a bolt in the slit of the connecting device, or snapped into place or latched, and by means of spring force held in this locked position. In this latched position, the spring must yet possess an additional (remaining) spring cushion that would still accommodate a temperature-caused expansion of the components. An expansion compensation took place up until now by means of a lengthwise compensation in displacement of the screw head. The head of the latched fastening element consequently protrudes, as is well known, somewhat above the surface of a component in order to guarantee a sufficient, additional spring cushioning. Nonetheless this is aerodynamically detrimental to the outer skin and results in an insufficient seal against a possible moisture penetration. That the Camloc connection also has no defined stop limit for the fastening element is also problematic. The available spring cushioning is too small and cannot be regulated.
The present invention provides a mechanically detachable connecting device for attachment of a windshield to a fuselage side frame of a viewing port of an aircraft, especially to the cockpit frame of a helicopter, which prevents deformation of the windshield and which, at the same time, adapts to the aerodynamic surface of the outer skin, diminishes mechanical stress caused by the connecting device, and avoids moisture penetration around the connecting device.
The connecting device is designed so that the seating element is attached with the fastening part inside the structure of the fuselage side frame. The connecting device has the advantage that it enables a defined spring cushioning for the retaining nut as well as for the retaining element. In contrast to a normal, floating rivet nut, the connecting device of the invention with defined spring excursion allows for motion of the entire connection. In the event of an expansion of the windshield as a consequence of temperature fluctuations, the attachment can yield in the direction of screwing about a defined spring cushioning. Cross-wise to this, a motion through the screwed joint with supporting disk with an enlarged bore hole diameter in the windshield is made possible. With an encapsulation of the housing element, the advantage is attained in that no moisture can penetrate into the interior of the cabin around the connecting device.
A further advantage is that the connecting device, in the region of the outer skin, can be completely incorporated into the flat contour of the outer skin so that no additional aerodynamic resistance is caused by the connecting device.
According to an additional configuration, it is also possible to make the fastening part subject to visual inspection in connection with an encapsulated seating element through an insertable covering partition.
The seating element has guide components designed in the axial direction for guiding the retaining nut. According to a further configuration, the spring cushioning of the spring device is axially adjustable.
The retaining nut possesses an integral self-locking mechanism to prevent a separation or resetting of the nut.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.